Arrangement for feeding ink into the output nozzle of a writing instrument



Jan. 3, 1967 E. ASCOLI 3,296,624

ARRANGEMENT FOR FEEDING INK INTO THE OUTPUT NOZZLE OF A WRITING INSTRUMENT Filed Nov. 24, 1964 3 Sheets-Sheet 1 INVENTOR BY MY 4 Jan 3, 1967 E, Ascou 3,296,624

ARRANGEMENT FOR FEEDING INK INTO THE OUTPUT NOZZLE OF A WRITING INSTRUMENT Filed Nov. 24, 1964 v 5 Sheets-Sheet 2 INVENTOR zZ/vzo 14 5:04/

ATTORNEY Jan. 3, 1967 E ASCOLI 3, 96,624

ARRANGEMENT FOR FEEDING INK INTO THE OUTPUT- NOZZLE Filed Nov. 24, 1964 FIG. 31.1

OF A WRITING INSTRUMENT Y 5 Sheets-Sheet 3 INVENTOR BY M ATTORNEY Un wd a e Pat n 3,296,624 ARRANGEMENT FOR FEEDING INK INTO THE 'OUTPUT NOZZLE OF A WRITING INSTRUMENT Enzo Ascoli, Lausanne, Vaud, Switzerland, assignor to Paillard S.A., Vaud, Switzerland, a corporation of Switzerland Filed Nov. 24, 1964, Ser. No. 413,455 Claims priority, application Switzerland, Dec. 17, 1963, 15,436/63 3 Claims. (Cl. 346-140) Witha view to obtaining a proper operation of the instrument, it is of advantage for the pressure of ink to be only slightly less than that producing a flow of ink out of the nozzle. Under such conditions, the operation of the arrangement is a delicate matter since in the absence of any electrostatic field, there is a risk of an untimely flow of'ink under the action of outer agents. Such a flow of ink may for instance be produced by vibrations or shocks to which the machine including the writing instrument' may be subjected.

Now, any fortuitous flow of ink risks dirtying the outer surface of the nozzle and consequently completely modifying the shape of the ink meniscus which changes in its turn the features of the ink projecting means and may even make them unfit for use as long as a complete cleaning which is quite an intricate operation has not been performed.

The present invention has for its object to remove such drawbacks and it covers an arrangement for feeding ink into the output nozzle of a writing instrument to produce a jet' of ink by means of an electrostatic field, said arrangement including an ink container connected through a pipe with said nozzle while, according to the invention, there is inserted an electrically controlled pump between the nozzle and ink container, which pump is designed so as to ensure, under the action of an electric control system, the setting under a predetermined'pressure of the ink feeding the nozzle.

The accompanying drawings illustrate diagrammatically and by way of example two preferred embodiments of the invention. In said drawings:

FIG. 1 is a diagrammatic illustration of a first em bodiment, i

FIG. 2 illustrates the second'embodi'rnent.

FIGS. 3a, 3b and 3c illustrate, on a much larger scale, the end of an ink output nozzle for different conditions of operation.

FIG. 4 is a graph showing the operation of the pump.

Turning to FIG. 1, a container 1 carrying a volume of ink 2 is connected through a pipe 3 with a pump 4 and thence with a further pipe 5 opening into the ink output nozzle 6.. 7

The pump 4 is constituted by a glass cylinder 7 inserted in a main body 8 made of insulating material, said main body 8 being provided at each end with a threaded section adapted to receive the connecting members 9 and 10. The connecting member 9 is rigid with an extension 11 entering the glass cylinder 7, which extension is furthermore provided with a channel 12 opening into the pipe 5. The connecting member 10 is also provided with 3,296,624 Patented Jan. 3,. 1 967 an inner channel 13 connected with the pipe 3' fed by the container.

Inside the glass cylinder 7 is inserted a pistion 14 of soft chromium-plated and polished iron which may slide very freely, with a comparatively large clearance, inside the cylinder 7. The stroke of said piston 14 is limited, on the one hand, by the inner end of the connecting member 10 and, on the other hand, by the extension 11 of the connecting member 9. i

The main body 8 made of insulating material serves as asupport for an outer winding 15 which, when it is energized by an electric current, produces a magnetic field exerting on the piston a force urging it upwardly. Said movement of the piston 14 produces of course an increase in the pressure of the mass of ink filling the space between said piston and the nozzle 6 and this increase in pressure is chiefly defined by the electromagnetic force exerted on the piston, by the weight of the latter and by the clearance provided between the piston and the wall of the glass tube 7.

While the piston 14 moves upwardly under the action of the magnetic field, the mass of ink corresponding to the volume of ink thus shifted flows out through the clearance between the piston 14 and the glass tube 7. The throughput of ink flowing out of the nozzle 6 is negligible with reference to the throughput in the clearanceand it is compensated by a corresponding modification in the speed of shifting of thepiston.

Obviously, the flow of ink out of the nozzle 6 should stop at the latest at the movement at which the piston 14' reaches the extension 11 forming a stop for it. If the piston has a diameter of a magnitude of 7 mm. with a stroke of 5 mm., the duration of its complete travel is sufilcient for the writing of about 200 written symbols of a conventional size without any stopping. Since it is an easy matter to synchronize the energization of the winding 15 with the control of the electrostatic field which is to urge ink out of the nozzle 6, the result is that at each interruption of the electrostatic field, the magnetic field is also cut off, which allows the piston 14 to then execute a fraction or the totality of its downward stroke under the action of gravity.

FIG. 4 is a graph showing the force of electromagnetic attraction exerted by the winding 15 on the piston 14 as a function of the position of said' piston. The shifting X of: the piston is given out on the abscissae and the force F on the ordinates. The starting point 0 of the graph corresponds to the position of the piston 14 at a point registering with the. middle point of the winding 15, which position cannot be actually reached in practice by reason of the presence of the extension 11 which acts as astop. The curve illustrating the force of magnetic attraction exerted onthe piston shows. a substantially hori; \l/

zontal section X X and consequently between the points X and X the variations of said force with the position of the piston are very slight as shown .at e and negligible in practice. Thepossible length of stroke allowed for the piston 14 is thus limited by the members 10and 11 between said points X and X It should :be remarked that the parts of the members 10 and 11 engaging the piston 14'respectively for two extreme positions of the latter have a bulging shape, so as to cut out the possibility of. an undesirable adherence between the piston and one of the stops. Furthermore, the pump 4 is arranged vertically so as to reduce tothe utmost the lateral friction which might arise between the piston 14 and the glass tube 7.

Preferably, the current energizing the pump 4 is adjusted to a value such that the magnetic force attracting the piston 14 may be equal to twice the weight of the latter. Thus, the force produced during the upward stroke of the piston is equal to the force of gravity ensuring its downwardmovement. Undersuch conditions, the increase and reduction in pressure applied to the ink in the nozzle 6 with reference to static pressure are of equal magnitudes.

FIGS. 3a, 3b and 3c illustrate cross-sectionally on a larger scalethe end of the nozzle 6 with ink therein for dilferent pressures exerted on the ink. FIG. 3w shows that under inoperative conditions the surface 16 of ink at the output end of the nozzle 6 is substantially flat.

FIG. 3b shows that said surface 6 is transformed into a convex meniscus during the upward movement of the piston 14 and lastly FIG. 30 showssaid meniscus. during the transformation-into a concave meniscus of thesame curvature during the downward movement of the piston 14. It should be remembered that the modifications in pressure produced by the pump 4 do not lead to any flow of ink out of the nozzle except in the case of FIG. 3b when a sufiicient electrostatic field is generated across the end of the nozzle 6.

FIG. 2 illustrates a modification wherein, as in the case of FIG. 1, the nozzle 6 is arranged substantially at the same level as the ink 2 in the container 1. The bottom of the container 1 forms a body 17 outwardly carrying a winding 18 surrounded in its turn by a permanent magnet 19. As illustrated in FIG. 1, a glass tube 20 carrying a piston 21 is arranged inside the body 17; the piston 21 is provided at each end which stops as shown at 22 and 23 respectively and it slides as precedingly with a clearance inside the glass tube 20. The ink carried in the container 1 reaches the upper surface of the piston 21 through a channel 23 whereas the ink lying underneath the piston 21 inthe lower section of the tube 20 may reach the nozzle 6 through the agency of a yielding pipe 25.

In said embodiment according to FIG. 2, the action of the magnet 19 on the piston 21 is sufficient for returning the latter into its upper inoperative position. The winding-energizing current is adjusted to a value allowing compensating almost exactly the action of the permanent magnetic field. Thus, as soon as the winding 18 is energized, the piston 21 moves downwardly under the action of gravity. When the electrostatic field which is to produce a jet of ink out of its nozzle 6 is out 01f, the energization of the winding 18 is switched off and the field produced by the permanent magnet 19 urges the piston 21 upwardly.

In either of the two embodiments described, the adjustment of the pressure required for operation may be readily executed either through a modification in the energizing current or through a modification in the level of ink in the container with reference to the nozzle 6.

It is obviously possible to provide numerous modifications and to replace for instance the pump of the piston type by a diaphragm pump. In the case where the actual time required for writing should be large when compared to the duration of the interruption, it may be of advantage to'provide a non-returnrvalve in the hydraulic circuit between the container and nozzle so as to prevent a return flow out of ink from the nozzle into the container, while the pump piston returns into its starting position vunder the action of a force which is several times larger than that producing its operative stroke. However, a particular advantage of the embodiments described hereinabove resides in that they include a single movable part, to wit the piston, and no further movable part such as :a valve or a flap valveis required.

I claim: 1. In a writing instrument, the combination of an ink container, an output nozzle, a connection between said container and said nozzle, a pump including a cylinder inserted longitudinally in said connection, the ends of said cylinder communicating respectively with the nozzle and with the container, and a piston of magnetic material adapted to be shifted inside said cylinder with a substantial clearance with reference theretobetween a first position nearer the container end of the cylinder and a second position nearer the nozzle end of the cylinder, the pressure of said pump being of a value sufiicient to form a miniscus at the outer end of said nozzle but insufiicient to burst said miniscus, means urging the piston towards its first position and means adapted to transiently produce a magnetic field urging the piston into its second position,

. the flow of ink out of said nozzle only occurring when a suflicient electrostatic field is generated across the end thereof. 2. In a writing instrument, the combination of an ink container, an output nozzle, a connection between said container and said nozzle, a pump including a cylinder inserted longitudinally in said connection, the ends of said cylinder communicating respectively with the nozzle and with the container, and a piston of magnetic material adapted to be shifted inside said cylinder between a first position near the container end of the cylinder and a second position nearer the nozzle end of the cylinder, the pressure of said pump being of a value sufiicient to form a miniscus at the outer end of said nozzle but insufficient to burst said miniscus, stops of a reduced area through which the movement of the piston inside the cylinder is limited in both directions, means urging the piston towards its first position and means adapted to produce transiently a magnetic field urging the piston into its second position, the flow of ink out of said nozzle only occurring when a sufficient electrostatic field is generated across the end thereof.

3. In a writing instrument, the combination of an ink container, an output nozzle, a connection between said container and said nozzle, a pump including a cylinder inserted longitudinally in said connection, the ends of said cylinder communicating respectively with the nozzle and with the container, and a piston of magnetic material adapted to be shifted inside said cylinder between a first position nearer the container end of the cylinder and a second position nearer the nozzle end of the cylinder, the pressure of said pump being of a value suflicient to form a miniscus at the outer end of said nozzle but insufiicient to burst said miniscus, a permanent magnet generating a magnetic field urging the piston into its first position and an electric winding coaxial with the cylinder and adapted when energized to produce a magnetic field predominating over the field of the magnet to allow a return movement of the piston into its second position, the flow of ink out of said nozzle only occurring when a sufficient electrostatic field is generated across the end thereof.

References Cited by the Examiner UNITED STATES PATENTS 458,873 9/1891 -De Poele 1o3-53 2,604,851 7/1952 Archibald 103-53 3,169,821 2/1965 Miller 346 FOREIGN PATENTS 554,308 6/1943, Great Britain.

RICHARD B. WILKINSON, Primary Examiner.

LOUIS J. CAPOZI, Examiner.

J. W, IIARIARY, Assistant Examiner. 

1. IN A WRITING INSTRUMENT, THE COMBINATION OF AN INK CONTAINER, AN OUTPUT NOZZLE, A CONNECTION BETWEEN SAID CONTAINER AND SAID NOZZLE, A PUMP INCLUDING A CYLINDER INSERTED LONGITUDINALLY IN SAID CONNECTION, THE ENDS OF SAID CYLINDER COMMUNICATING RESPECTIVELY WITH THE NOZZLE AND WITH THE CONTAINER, AND A PISTON OF MAGNETIC MATERIAL ADAPTED TO BE SHIFTED INSIDE SAID CYLINDER WITH A SUBSTANTIAL CLEARANCE WITH REFERENCE THERETO BETWEEN A FIRST POSITION NEARER THE CONTAINER END OF THE CYLINDER AND A SECOND POSITION NEARER THE NOZZLE END OF THE CYLINDER, THE PRESSURE OF SAID PUMP BEING OF A VALUE SUFFICIENT TO FORM A MINISCUS AT THE OUTER END OF SAID NOZZLE BUT INSUFFICIENT TO BURST SAID MINISCUS, MEANS URGING THE PISTON TOWARDS ITS FIRST POSITION AND MEANS ADAPTED TO TRANSIENTLY PRODUCE A MAGNETIC FIELD URGING THE PISTON INTO ITS SECOND POSITION, THE FLOW OF INK OUT OF SAID NOZZLE ONLY OCCURRING WHEN A SUFFICIENT ELECTROSTATIC FIELD IS GENERATED ACROSS THE END THEREOF. 